Improvement in processes for making illuminating-gas from wood



driven ott at a low temperature.

UNITED 'STATES PATENT OFFICE lVILLIAM P. MCOONNELL, OF \VASIIIXGI`ON, DISTRICr1 OF COLUMBIA;

IMPROVEMENT IN PROCESSES FOR MAKING lLLUMlNATlNG-GAS FROM WOOD.

Speciiication forming part of Letters Patent No. 11,740, dated September .26, 1854.

To @ZZ whom t may concern:

Be it known that I, WILLIAM I). McCon- NELL, of IVashington, in the District of Columbia, have invented a new and useful Improvernent in Making Gas from XVOOd, of which the following is a full, clear, and exact description, reference being made to the accompanying drawing, which represents the heating and purifying apparatus in section.

The figure shows a sectional elevation of the apparatus.

I'Iitherto in the destructive distillation of wood for preparing charcoal or pyroligneous acid or gas for the purpose of illumination, it has been usual to condense the vapors immediately after leaving the retort, and in this way large amounts ot` tar and oils were run ott. The gas obtained in such cases is always poor, and burns with a blue Hame,being deiicient in carbon if the gas is washed and containing too much carbon it' not washed, in the latter condition the carbon being in the form of smoke. I have discovered that by subjecting the gaseous and volatile products of the resinous woods to a high degree of heat after they leave the retort the gas may be procured for illumination of an excellent quality, giving a bright light, and at much less cost than gas from coal, rosin, or oil. The amount ot` tar is greatly diminished, nearly all being converted into gas, while the pyroligneous acid is more readily condensed and in a purer state than when There are various ways of subjecting the gases and vapors to a high degree of heat; but when it is done by the apparatus represented in the drawing there are particular advantages. I have found it advantageous to expand the gases into a large heater instead of passing them through contracted pipes, which latter would apply the heat more rapidly, but witlr out the beneficial results of the former.

'lo effect the heating and p uritication of the gas I provide a receiver A, inclosed within a receiver B, making the tine-space between A andB about equal to the space B; or, in other words, the cross-section of the two chambers of equal area. rlhe outer receiver B has a Iiange g at the top, upon which is bolted the cover b, and into this cover is inserted the escape-pipe (l. The inner receiver is also closed with a tight cover, into which is i nsert-ed the induction-pipe O, this pipe passing tight-ly through the cover b of receiverB. The outer receiver is provided with two lugs to sustain it when set on masonry. The under receiver h has an opening at the bottom, through which the gases pass into the outer receiver. Over this opening I place a grate g', upon which I sometimes place brick or similar materials, through which the gas is to pass. The receivers are kept at proper dis tances by suitable projections e e attached to either receiver. The gas ascends between the receivers and out the exit-pipe, and may be taken thence directly to the gasometer, where the pyroligneous and empyreumatic products are readily absorbed and precipitated,`the quantity being so small as not to require a separate washer. I may use an independent washer, but it is not necessary, the odor of the wood-gas being less oensive than from'gases obtained from coal, rosin, or oil. It is not essential to specify any degree of heat to be used in this process; provided, only, that in the rst stage of the process the heat be 'suflicient to effect the destructive distillation of Wood, and that in the second stage of the process the gases and vapors be subjected to a degree of heat higher than that necessary to eect the decomposition of the wood, and this is the sense in which I use the expression high degree of heat. It may be more or less, but usuallyin apparatus of small size the ou ter surface of the reheating-retort attains a low red heat. In larger works the temperature may be higher.

I will remark here that the usual process of operation with either coal, rosin, or oil will not answer in making gas from wood. IVithout the second heating the making of gas from wood suitable for common use is entirely impracticable.

I am aware that gas has been subjected to a high heat after leaving the retort when obtained from other materials, and in some cases with beneficial results; but I am not aware that it was ever contemplated to apply that process to wood-gas, and I am not aware that wood-gas has ever been introduced prior to my discovery. I have found wood-gas so made far more economical and agreeable and more brilliant than other gas, and having been the first to make this important disomv duets of destructive distillation therefrom to ery I desire to secure it to myself, and to prea high degree of heat, substantially in the Vent others from using the same without my manner and for the purposes herein set forth. consent.

VVhat I claim, therefore,'as my invention and discovery is- Witnesses:

The improvement herein described in Inak- I. BIGELOW, ingl gas from Wood-viz., subjecting the pro- THOS. DONOHO.

WM. P. McooNNELL. 

